Mysterious holes in the Aswan Quarry
Geological Description and Observations
Author: Drs. E. van der Ziel
Introduction
The Aswan quarry is located in the city of Aswan, Upper Egypt (Fig 1). The quarry has been actively used throughout historical times to mine granite for the construction of buildings, temples, statues, and other artifacts. Mining activities by the Ancient Egyptians (as early as the Old Kingdom), Romans, and Arabs have been recorded in this area. We find the Aswan granite throughout Egypt at cultural locations. Present-day Aswan granite is still mined.
The geology of Aswan is dominated by outcrops of Precambrian crystalline rocks overlain by Cretaceous Nubian sandstone formations (Roden et al. 2011). The Precambrian crystalline rocks, which include the granite plutonic bodies, outcrop in the region of Aswan city and Elephantine Island. Granite rock can be observed outcropping as you sail across from Aswan to Elephantine Island. The Author of this paper visited Elephantine Island and the Aswan Quarry in September 2022.
The granite of the Aswan Quarry is characterized by a rose color and large size crystals. Different minerals can be clearly distinguished by the eye (Fig 2).
Observations on Structural Setting and Tool Marks
In the Aswan Quarry, a geological natural fracture trend can be observed: faults in a dominant EEN-WWS direction are present in the granite outcrop. In an areal map view, this trend can best be observed (Fig.3).
The rose granite crystallized out of magma deep within the earth’s crust during the Precambrian 1 to 4 billion years ago. The natural fractures would have formed when the granite plutonic body was uplifted to the earth’s surface. This uplift event is linked to a regional tectonic event called the “Nubian Swell” that caused the uplift and exposure of Precambrian crystalline rocks in the region of Aswan some 200mln yrs ago during the Mesozoic (Turnmond et al. 2004).
The unfinished obelisk is carved out in line with the orientation of the naturally occurring faults in the outcrop, indicating that the Ancient Egyptians understood geological trends and made the best use of the natural fractures — i.e. weak zones — to carve out the Obelisk.
On and near the unfished obelisk we observed areas of multiple “indented squares” or “scoop marks” on the surface of the granite, all with similar dimensions of ~40x40cm.
Various other tool marks were also observed in the Aswan Quarry related to mining activities from different time periods (Fig 7).
At the quarry site other mysterious holes were observed (Fig 5). These holes are referred to as “test holes” as the current explanation is that these holes were drilled in the granite to test the quality of the rock.
The mysterious “test holes” are 1 to 1,5m wide in diameter, and 1 to 5 m deep. We observed multiple of these holes on the Quarry site. The markings on the hole surfaces have a rock-on-rock carving signature and locally also some “scooped marks” have been observed on the surface of the holes. The age and function of the “test holes” are unknown.
The “test holes” do not align with the previously described geological trend. The holes seem to be carved straight down into undeformed granite independent of any geological trend.
On the Southwest side of Elephantine Island, similar holes were observed in a granite outcrop near a house (Fig 5).
The holes seem to be carved straight down into undeformed granite independent of any geological trend. No mechanical tool marks were observed on the hole surfaces. On Elephantine Island, similar holes were observed in an area where the granite outcrops 5e and 5f. Photographs by Author.
Semi-equal size indented squares are observed on and near the unfinished obelisk. The “scoop marks” are ~40x40cm. The dimensions seem to coincide with an arm’s length scraping motion movement: a grinding/scraping motion with a dolerite ball and some water on the granite surface was tested at the outcrop (Sept 22) and resulted with effect in a slight and smooth indent at the surface. Photographs by Author.
Discussion and Interpretation
The unfinished obelisk was carved out making the best use of the geological trend and natural weak zones in the granite. This indicates the ancient Egyptians understood geology and rock properties. The humanoid corridor present around the unfinished obelisk indicates the obelisk was carved out by hand by humans.
Many dolerite balls were found present at the outcrop and the current model is that dolerite balls were used to carve out the granite. (Dolerite has a higher density of 2.6–3.0 kg/m3 vs. granite with a density of 2.6–2.7 kg/m3).
The author visited the site on Sept 22 and tested this model with other visitors: they established that with a grinding/scraping motion, using a dolerite ball and some water at the granite surface, the granite was carved off, leaving significant “scrape-off residue” at the surface, and the motion resulted in a feelable slight and smooth curved indent (~0.01 to 0.1 cm) at a surface of 20x5 cm after about ~1 min. The grinding/scraping motion by hand was most comfortably exercised across half an arm’s length distance which exactly corresponds to the dimensions of the observed “scoop marks” on and around the unfished obelisk.
This model provides an explanation for the observed “scoop marks” on the obelisk and honors the current model that dolerite balls were used to carve out the obelisk. Introducing the element of time, many human workers, a workday of 8hrs, and the assumption of one worker per 6 scoop mark areas — it is estimated the obelisk could have been carved out in 1.5 to 17 years using this technique (table 1).
This estimation does not consider any geological “weak zones” (fault zones) as the estimated rate of “scrape off” was done on a piece of undeformed granite. Considering areas of weakness surrounding the obelisk the timeframe could have been further reduced. This effect was not estimated or incorporated in the current time estimation.
The “scrape off” rate range was empirically estimated on a ~20x5 cm surface during a live test on site (Sept 22). *It is estimated that per surface area around 3 meters “depth” had to be scraped off around the obelisk in order to carve it out.
Multiple mysterious “test holes” are present in the Aswan Quarry and one on the Southwestern side of Elephantine Island (fig 5). More holes could be present in the wider area and mapping out where these holes are present would possibly help to better understand their purpose and function.
The current model is that these holes were carved out to test the rock quality of the granite. This article would like to challenge this model as it does not make sense: The granite outcrop is a homogeneous rock body and you would not need multiple “test holes” in short distance of each other to understand the quality of the rock as the rock is homogeneous across the entire outcrop. Other rock quality features, like weak spots related to geological fracture trends or non-granite rock intrusions, can be clearly observed from the surface and do not require test holes to understand.
The “test holes” surfaces do not bear any mechanical tool markings and locally show the scoop marks. This indicates the holes were likely carved out using the same rock-on-rock technique as for the obelisk. It is estimated that one worker would need 1,3–14 years to carve out a “test hole” of 1m diameter and 3m deep into the granite using the dolerite on granite “scrape off” technique (table 1).
Ancient Egyptians demonstrated to have a geological understanding of the outcrop in the way they chose to carve out the obelisk. The holes seem to be carved straight down into undeformed granite independent of any geological trend and therefore seem to “mismatch” the obelisk mining activities. This could mean 1. The “test” holes were carved out by humans not understanding geological trends (pre or post-Ancient Egyptian?) 2. The holes had a different function and were purposely chosen to be carved in those locations/orientations.
Speculation on Function of Mysterious “test holes”
The holes do not seem to carve out a granite body, so the function was not to mine granite rock, unlike all the other mining activities. The holes themselves seem to have been the objective. This article questions the function as a test hole but what else could it be?:
1. Could the function have been for an engineering purpose? Could the holes have been used as a stabilizing base for any engineering constructs used for mining? Mapping out the exact locations and dimensions of the holes and conceptually modeling what sort of engineering construct could have been used in the quarry, and fitted to the holes, would help to better indicate this function.
2. Could the function have been architectural? Could the holes have been used as a stabilizing base for buildings or statues? Mapping out the exact locations and dimensions of the holes and trying to identify any architectural/geographical trends would help to indicate this function. The fact that more holes are located in the wider area, in the Southwest of Elephantine Island outside of the quarry, could be interpreted in line with an architectural function as this would have wider geographical applicability.
3. Could the function have been meditative of a form or punishment? spending years scraping off the rock without a purpose? Was there a deeper meaning to the art of doing extremely difficult non-functional activities? Maybe we are not fit to understand this because we a product of our effectiveness and productivity-focused society. This mindset could have been very different in the past considering the fact that Ancient Egyptians are known to have spent entire lifetimes on one project e.g. building tombs for the afterlife.
Conclusions
The unfinished obelisk is carved out in line with the orientation of the naturally occurring faults in the outcrop, indicating that the Ancient Egyptians understood geological trends and made the best use of the natural fractures — i.e. weak zones — to carve out the Obelisk. The mysterious “test holes” do not align with the previously described geological trend. The holes seem to be carved straight down into undeformed granite independent of any geological trend.
“Scoop marks” of ~40x40cm are observed at and near the unfinished obelisk. The dimensions seem to coincide with an arm’s length scraping motion movement: a grinding/scraping motion with a dolerite ball and some water on the granite surface was tested at the outcrop and resulted with effect in a slight and smooth curved indent at the surface.
An empirical estimation of the “scrape off” rate was made during a test on site on Sept 22. Assuming many human workers, a workday of 8hrs, and one worker per 6 scoop mark areas — it is estimated the obelisk could have been carved out in 1.5 to 17 years. Accounting for “weak zones” this timeframe could be further reduced. For a “test hole” of 1m diameter and 3m deep into the undeformed granite and one worker would need 1,3–14 years to carve out the holes using the dolerite ball “scrape off” technique.
This paper challenges the current model of a “test hole” function for the mysterious holes present in the Aswan quarry. The paper proposes other functions but cannot make any conclusions. The age and function of the mysterious holes remain unknown. Mapping out the exact locations and dimensions of the holes would however help to better indicate this function and it is therefore recommended for future work.
About the author
Drs. Eveline van der Ziel
Eveline holds a master’s degree in Geology from the VU University Amsterdam (cum laude). She is a professional geologist with 10+ years of energy industry experience and research background in carbonate sedimentology. She conducted ample geological fieldwork in Europe and the Middle East throughout her career. Eveline currently works as a new business development manager in the renewable energy sector. Since childhood, Eveline has been fascinated by our ancient past and in her spare time she likes to research various related topics.
References
Turnmond et al. 2004. The Nubian Swell. Article in Journal of African Earth Sciences
Roden et al. 2011. Structural influence on the evolution of the pre-Eonile drainage system of southern Egypt: Insights from magnetotelluric and gravity data Article in Journal of African Earth Sciences.
